This invention relates to water pumps for marine propulsion devices and, more particularly, to the impeller-drive shaft assembly of such a water pump.
Water pumps in marine propulsion devices typically have rubber vaned impellers that are eccentrically located in the pump chamber. Such an impeller in inherently unevenly loaded, and this causes a wearing action between the impeller hub and the drive shaft with each rotation.
Typical means for the driving of the impeller hub by the drive shaft are, for example, bonding, set screws, through bolts, press fits, and interference fit keys. These means often result in corrosion problems and difficulty in installation or removal. Furthermore, with extended operation, the wearing action between these drive mechanisms and the impeller hub can cause damage to either member and can ultimately result in failure of the water pump. This is especially true when the water pump is operated in an abrasive environment.
Attention is directed to the following U.S. patents which disclose pump impeller-shaft assemblies.
______________________________________ Patentee Patent No Issued ______________________________________ Shortt 150,261 April 28, 1874 Gilbert 368,468 August 16, 1887 Gray et al. 550,019 November 19, 1895 Barbour 599,824 March 1, 1898 Davis 634,660 October 10, 1899 Hawksworth 641,106 January 9, 1900 Boss 687,393 November 26, 1901 Veitch, Jr. 2,883,838 April 28, 1959 Steiner 3,438,660 April 15, 1969 Swiderski et al. 3,994,608 November 30, 1976 Schonwald et al. 4,172,678 October 30, 1979 ______________________________________
Attention is also directed to co-pending Bland application Ser. No. 560,593, filed on Dec. 12, 1983, now U.S. Pat. No. 4,592,733 and entitled "Water Pump For Marine Propulsion Devices."